Last week, Sigur Rós posted a video teasing the release of "surprise film event" Inni. And after stirring up an appropriate amount of frothing anticipation, they've hit us with the details. Inni, it turns out, is both a live film and a double live album, and it's coming from XL in November.

Vincent Morisset, the man behind Arcade Fire's Miroir Noir, filmed Sigur Rós as they played their last show before starting an indefinite hiatus at the end of 2008. The show, at London's Alexandra Palace, was also the first Sigur Rós show where they played as their core four-piece lineup, without the help of string quartet Amiina, since the earliest part of the last decade.

Morisset filmed the band digitally, then re-filmed that footage on 16mm, then refilmed it all again, "sometimes through prisms and other found objects," according to a press release, so expect Inni to be artier and more aesthetically varied than most concert films. The band's in-house recording engineer Birgir Jón Birgisson, meanwhile, recorded the live album. It runs an hour and 45 minutes, and it includes the entire Alexandra Palace show minus one song.

The film will debut September 3 at the Venice Film Festival.